On my tf300t ASUS tablet (with wifi only) I tried to set "Restrict Background Data" following

Settings->Data Usage->three boxes in the upper right corner,

but there is no such option. I read on some forums that this option is only available with limited mobile data, but the option to set a limit is not available under Settings->Data Usage->three boxes in the upper right corner.

There is, however, an option under

Settings ->Developer Options -> Background process limit,

but I'm not sure about it. On my Gingerbread phone, background processes were disabled, and whenever I wanted to download an app, I had to enable it. With the Backround Process limit, however, downloading is possible (therefore, I'm not sure if this is the equivalent to Gingerbread's setting). Furthermore, I noticed that, after setting Background Process limit, every once in a while I get a message that some Asus process has been terminated. My question is: how would one disable background processes (no connections to wifi while screen off, ...) in order to save the battery?

Maybe that option is not available in wifi only tablets. Usually you restrict data because you have limited data on your mobile plan, where wifi you (usually) don't have that limit.
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Ryan ConradFeb 3 '13 at 14:42